Charge

Pump

Driver

UVLO

Current

Limit

Thermal

Sense

IN

GND

EN

ILIM

OUT

FAULT

CS

Reverse

Voltage

Comparator

-

+

Current

Sense

(Note A)

8-ms Deglitch

Copyright © 2016, Texas Instruments Incorporated

13

TPS2552D, TPS2553D

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SLVSDL7 – SEPTEMBER 2016

Product Folder Links: TPS2552D TPS2553D

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Copyright © 2016, Texas Instruments Incorporated

9 Detailed Description

9.1 Overview

The TPS2552D and TPS2553D are current-limited, power-distribution switches using N-channel MOSFETs for

applications where short circuits or heavy capacitive loads will be encountered and provide up to 1.5 A of

continuous load current. These devices allow the user to program the current-limit threshold between 75 mA and

1.7 A (typ) via an external resistor. Additional device shutdown features include overtemperature protection and

reverse-voltage protection. The device incorporates an internal charge pump and gate drive circuitry necessary

to drive the N-channel MOSFET. The charge pump supplies power to the driver circuit and provides the

necessary voltage to pull the gate of the MOSFET above the source. The charge pump operates from input

voltages as low as 2.7 V and requires little supply current. The driver controls the gate voltage of the power

switch. The driver incorporates circuitry that controls the rise and fall times of the output voltage to limit large

current and voltage surges and provides built-in soft-start functionality. There are two device families that handle

overcurrent situations differently. The TPS255xD family enters constant-current mode when the load exceeds the

current-limit threshold.

9.2 Functional Block Diagram

A.

TPS255x parts enter constant current mode during current limit condition

9.3 Feature Description

9.3.1 Overcurrent Conditions

The TPS2552D and TPS2553D respiond to overcurrent conditions by limiting their output current to the IOS levels

shown in Figure 23. When an overcurrent condition is detected, the device maintains a constant output current

and reduces the output voltage accordingly. Two possible overload conditions can occur.

The first condition is when a short circuit or partial short circuit is present when the device is powered-up or

enabled. The output voltage is held near zero potential with respect to ground and the TPS2552D and

TPS2553D ramps the output current to IOS. The TPS2552D and TPS2553D devices limits the current to IOS until

the overload condition is removed or the device begins to thermal cycle.

The second condition is when a short circuit, partial short circuit, or transient overload occurs while the device is

enabled and powered on. The device responds to the overcurrent condition within time tIOS (see Figure 21). The

current-sense amplifier is overdriven during this time and momentarily disables the internal current-limit

MOSFET. The current-sense amplifier recovers and limits the output current to IOS. Similar to the previous case,

the TPS2552D and TPS2553D devices limit the current to IOS until the overload condition is removed or the

device begins to thermal cycle.